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2.0 Python: Variable Names

A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume).

2.1 Rules for Python variables​

  • A variable name must start with a letter or the underscore character
  • A variable name cannot start with a number
  • A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
  • Variable names are case-sensitive (age, Age and AGE are three different variables)
  • A variable name cannot be any of the Python keywords.

Example 2.1.1​

Legal variable names:

myvar = "John"
my_var = "John"
_my_var = "John"
myVar = "John"
MYVAR = "John"
myvar2 = "John"

Example 2.1.2​

Wrong

Illegal variable names:

2myvar = "John"
my-var = "John"
my var = "John"

Remember that variable names are case-sensitive

2.2 Multi Words Variable Names​

Variable names with more than one word can be difficult to read.
There are several techniques you can use to make them more readable:

2.2.1 Camel Case​

Each word, except the first, starts with a capital letter:

myVariableName = "John"

2.2.2 Pascal Case​

Each word starts with a capital letter:

MyVariableName = "John"

2.2.3 Snake Case​

my_variable_name = "John"